In article <19981114110719.18674.00000589 at ngol07.aol.com>,
tonyjeffs at aol.com (TONYJEFFS) wrote:
> Sorry. I don't know what wentwrong with my previous 'text-less' post.
>>> A few comments on the paper in Nature Medicine:
>> Summary of experiment.
> Five Cancer patients were given a chemical that marks cells undergoing
> division. It is therefore useful in assessing the spread of cancer and was
> administered as part of their treatment, but the marker cell will also show
> cytogenesis in other cells, such as in this instance nerve cells in the
> hippocampus, so it is useful in research..
> The patients unfortunately died of their illness. The researchers obtained
> permission to examine their brains post-mortem.
> They also looked at the brain of a sixth cancer victim who had not been given
> the marker chemical.
> The Dentate gyrus, part of the hippocampus, of the first five subjects showed
> evidence of neuron division.
> ...........................
> Some comments (from a novice):-
> 1. The control group didn't appear to control for anything much
> ...the patient who was not given the cell division marker did not show
evidence
> of cell division marker in his hippocampus...so what?
> 2. I don't understand how they eliminated the possibility that these dividing
> hippocampal cells were cancer cells.
> I think they could have controlled for this possibility by looking for
dividing
> cells in heart muscle, and in other brain regions. If there were dividing
> cells everywhere, it would cast doubt on their rsult.
I think you are being too hard on them. Remember, this research is
difficult to do and has already been done properly in rats, mice, and
monkeys. The cells, I think are probably granule cells (neurons), which
means they are not cancer cells. This is easy to tell from the appearance,
although I haven't looked at the paper that carefully. True cancerous
neurons are almost completely unheard of (the exception is
medulloblastoma; most brain tumors are glial or metastatic), but these are
not in hippocampus, plus it would be very easy to tell the difference
(VERY easy, I could do it), and these guys are hard core neuroanatomists.
Plus the morphology of the hippocampus is something these guys have seen
many times (including lots of human work) so there is no way they would
miss cancer cells.
Plus, you are forgetting THERE ARE dividing cells everywhere else. Noone
disputes this, what's new here is that neurons are dividing as well; in
adults. If you read a Neuroscience text, it will tell you this doesn't
happen, and the authors have built enough critical mass now to show this
isn't true...
Cheers,
Stephan
> 3. I was interested in the references - there are papers on mamalian
> hippocampal neuron regeneration going back to the 1960's.
>> (I'm not experienced in reading this sort of paper - still studying)
>> I have of the Nature paper on disk. Email me if you want a copy. (text only)
> Please be prepared to wait a few days.
>> Tony